A walking beam furnace of this kind is described in the German Offenlegungsschrift 34 40 126. In this walking beam furnace the slots in the floor have to be big enough to ensure free movement of the walking beam supports in the feed direction without jamming due to the unavoidable manufacturing tolerances and thermal expansions.
For a feed and lift each of e.g. about 300 mm and a support diameter of about 200 mm, the length of the floor opening therefore amounts to 600 mm and the width to about 300 mm. Thus outside the support region there is a free space about 400 mm in length and 100 mm in width. As there are a large number of these floor openings in the walking beam furnace considerable radiation losses occur, resulting in a considerable loss of heat.